When displaying a screen image of one or more target objects (echo image), conventional radar apparatuses suppress echoes that do not always continuously appear at the same location (e.g., sea clutters), and carry out scan-to-scan correlation processing for accentuating the echoes of the target objects (see JP11-352212A, for example).
However, when a moving speed of the target object is fast, an echo of the target object detected at a certain location during a predetermined scan may also be detected during the next scan at a location distant from the location of the last scan. In such a case, as a correlation of the two echoes at the same location becomes low, the echoes of the target object will be weakened by the scan-to-scan correlation processing.